JPH01251360A - Method for rewriting data of magneto-optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To realize a high-speed overwrite by irradiating a magneto-optical recording medium with a laser spot and modulating the direction of the magnetic field of an electromagnet, which keeps constant the distance from the magneto-optical recording medium, in a position opposite to an optical head. CONSTITUTION:A monolayer magneto-optical recording film is formed on one face of the disk substrate of a magneto-optical disk 1, the magneto-optical recording film is sandwiched between protective films to prevent oxidation and further, it is covered with resin. The magneto-optical recording medium is irradiated with a converged laser spot of fixed intensity, an electromagnet 4 having a height control mechanism to keep constant the distance from the magneto-optical recording medium is arranged in the position opposite to an optical head 2 with the magneto-optical recording medium inbetween, and by modulating the direction of the magnetic field generated by the electromagnet 4, the overwrite is attained. Thus, the high-speed overwrite from several 100kHz to several MHz can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a method of rewriting data by overwriting in a magneto-optical recording/reproducing device.

[Prior Art 1] In recent years, magneto-optical disks have been actively developed as rewritable large-capacity memories. (Nihon Keizai Shimbun, December 3, 1986). Regarding the technology of this practical magneto-optical disk device, please refer to IEICE Magnetic Recording Study Group materials, MR84-3
7-39 (1984) or IEEE Tran
s.

Magn, MAG-21, page 1624 (198
5 years) is described in detail.

In this device, at least two rotations are required to rewrite data. That is, in the first rotation, a bias magnetic field in the opposite direction to that during recording is applied, and the area to be rewritten λ by the continuously oscillating laser spot is erased. And the next 2
A bias magnetic field in the opposite direction to that during erasing is applied at the rotation point, and the laser is pulsed in accordance with new data to record new data. In optical discs, after recording, it is often necessary to confirm whether the recording was performed accurately, but basic data rewriting is performed in these two revolutions.

Data can be overwritten in normal magnetic recording devices, such as floppy disk devices, hard disk devices, and various magnetic tape devices (for computers, audio, and video). That is, in a floppy disk device or a hard disk device, data rewriting is completed in one rotation of the disk. Therefore, in the above example, it takes extra time to rewrite the data, and the waiting time of the host computer increases accordingly.

In other words, data processing efficiency is poor.

Therefore, a method of overwriting in magneto-optical recording has recently been proposed. First, the overwrite method (1
), there is 29P-ZE-14, which was announced at the 1985 Autumn Academic Conference of the Japan Society of Applied Physics. The basic principle will be explained with reference to FIG. Track n-1, n on the disk now
, n+1. These tracks are composed of a control track 101 and a recording track 100. A track address 105 is displayed on the control track 101.
There is. As a laser light source, a 3-array laser is used, and an erasing laser beam 102 and a control laser beam 103 are used.
A recording/reproducing laser beam 104 is focused onto the disk surface. First, when recording an n-2 track, recording is performed using a recording/reproducing laser beam with the bias magnet oriented as the south pole. At the same time, the n-1 track is erased by the erase laser beam 102. Then, when the recording/reproducing laser beam 104 comes to the n-1 track, recording is performed on the n-1 track with the direction of the bias magnet set as the north pole. In this way, overwriting can be achieved in a pseudo manner.

As the overwriting method (2), there is a method described in Nikkei Electronics, No. 419, pages 94-96. The basic principle will be explained with reference to FIG. This is a so-called magnetic field modulation method. A slider 109 and a magnetic head 110 are placed on a magneto-optical disk consisting of a substrate 106, a recording layer 107, and a protective layer 108 with a flying height 111 of 2 to 4 μm apart. The Iin air head 1 is continuously heated by the condensed laser beam 112 to increase the rewriting track.
Overwrite by 10. It is reported that overwriting of several MHz is possible using this method.

The overwriting method (3) is described in Nikkei Electronics, No. 419, pages 94-96. The basic principle will be explained with reference to FIG. This magneto-optical disk is composed of two layers of magneto-optical recording films. That is, the memory layer 113 and the auxiliary layer 114. Since the coercive force of the auxiliary layer is smaller than the coercive force of the memory layer, the lin formation is aligned downward by the preceding auxiliary magnet 115. When rewriting data, overwriting is performed by modulating the intensity of the laser beam at the location of the auxiliary 6th well stone 116. This takes advantage of the fact that the Curie temperature of the auxiliary layer is higher than that of the memory layer and that the magnetization direction of the memory layer follows the magnetization direction of the auxiliary layer. In this way, the old data 119 is overwritten and becomes new data 118. Note that 117 is the disk rotation direction.

[Problem to be solved by the invention] However, the above-mentioned conventional overwriting methods (1) to (3)
) has the following problems.

In overwrite method (1), data cannot be overwritten during random access; in other words, pseudo overwriting can be performed continuously from a specific track, but when a track to be rewritten is reached by random access, data is always overwritten for erasing. Requires extra rotation. Therefore,
It cannot be overwritten as combiator memory.

In the overwrite method (2), since the head flying height 111 is only 2 to 4 μm, a head crash occurs due to dust on the disk surface. That is, the optical disc cannot be inserted into or removed from the device. It must be a sealed type like a fixed magnetic disk drive, and the advantages of optical disks cannot be utilized.

In the overwriting method (3), since a two-layer magneto-optical recording film must be used, manufacturing is difficult and costs inevitably increase. Further, a leading auxiliary magnet 115 is required, but this magnet must generate a strong magnetic field, resulting in a large size. Therefore, regular optical disk cartridges cannot be used.

The present invention is intended to solve these problems, and its purpose is to accommodate an optical disk having a single-layer magneto-optical recording film in a cartridge and make it removable, thereby realizing non-pseudo overwriting. The purpose of the present invention is to provide a data rewriting method.

[Means for solving the problem] The data rewriting method of the magneto-optical recording and reproducing device of the present invention irradiates a magneto-optical recording medium having a single-layer magneto-optical recording film with a focused laser spot of a constant intensity. , by placing an electromagnet with a height control mechanism that keeps the distance from the magneto-optical recording medium constant at a position facing the optical head across the magneto-optical recording medium, and modulating the direction of the magnetic field generated by the electromagnet. It is characterized by overwriting.

〔Example〕

An embodiment of the present invention is shown in FIG. 1. The present invention is basically a magnetic field modulation system. Reference numeral 1 denotes a magneto-optical disk, in which a single-layer magneto-optical recording film is formed on one surface (the upper surface in the figure) of a disk substrate. Of course, the magneto-optical recording film is sandwiched with a protective film to prevent oxidation, and is further coated with 181 resin. 2 is an optical head equipped with a laser light source, a signal detection optical system for reproducing data from reflected light, and a servo optical system for tracking and focusing. 3 is a frame, which includes parts (4, 5, 6, 7, 8, 9) placed on the side facing the optical head 2;
, 10). The whole connected by the frame 3 is accessed in the track vertical direction by a linear motor or stepper motor. 4 is an electromagnet for magnetic field modulation. Reference numeral 5 denotes a coil bonded to the electromagnet 4. When a current is passed through the coil 5, a vertical force acts on the electromagnet 4 due to the action of the permanent magnet 6, and the height of the electromagnet 4 relative to the magneto-optical disk l changes. 7 is four wires that support the electromagnet 4 and the coil 5.

Now, in recent years, to reduce the cost of disks, plastics (polycarbonate, polymethyl methacrylate, epoxy) have been used as disk substrates.

In optical discs using plastic substrates, which are often made of polyolefin (such as polyolefin), the surface of the recording medium can oscillate up and down by several hundred micrometers (this is called surface oscillation), which is an order of magnitude higher than optical discs using glass substrates. is big,
Therefore, the mechanism and principle for detecting the height, which must detect the height of the electromagnet 4 with respect to the magneto-optical disk 1 and always maintain it at a constant height, will be explained with reference to FIG. 2.3.

FIG. 2 is a structural diagram of the height detection mechanism. 8 is a light emitting diode, 9 is a 2-split photodiode, lO is a light-emitting diode 8. 2-split photodiode 9 is 1! Light emitted from a light emitting diode 8, which is a mounting base for attaching to the magnet 4 and the coil 5, is reflected by the magneto-optical disk 1 and enters the two-split photodiode 9.

FIG. 3 is an explanatory diagram of the height detection method.

(b) shows when the electromagnet 4 is at the optimum position, and the light reflected by the magneto-optical disk 1 enters the center of the two-split photodiode 9. Therefore, if the difference between the respective outputs of the two-divided photodiodes is generated by the differential amplifier 11, the value becomes zero. When the magneto-optical disk 1 moves upward as shown in (a), the output of the differential amplifier 11 becomes positive. When the magneto-optical disk 1 moves downward as shown in (C), the output of the differential amplifier 11 becomes negative. Therefore, if the output of the differential amplifier 11 is controlled to be zero, the height of the magnet 4 can be kept constant.

FIG. 4 is a structural diagram of the electromagnet 4 and the height control mechanism. This figure is seen from the side of the magneto-optical disk l. The dimensions of electromagnet 4 are 6X6X1.8 (unit: mm), 1
2 is a ferrite core, 13 is a winding wire, and 2 wires are 30 μmφ.
It is made of 4 bundles of Litz wire wound in 26 turns.

A current equivalent to the recorded data is passed through this to overwrite the data. 5 is a coil glued to magnet 4, and 6 is a permanent magnet. Permanent magnet 6 is attached to frame 3.

FIG. 5 shows the magnetic field strength versus distance from the electromagnet. The magnetic field strength required for overwriting is at least about 100 δe (Oersteds). Therefore,
The distance can be up to 200 μm. Considering the size of dirt and dust on the disk surface, 100
Although a distance of .mu.m or more is required, this requirement can be satisfactorily met. Therefore, the distance between the electromagnet 4 and the magneto-optical disk I is controlled to always be 200 μm using the method described above. As a result, it becomes possible to attach and detach the magneto-optical disk. Furthermore, the electromagnet and surrounding parts are small in size, making it difficult to use a regular cartridge (with a single opening and
The shutter also has one 0. For example, ISO standard 5.25
It is possible to store the disc in a 3.5" magneto-optical disk cartridge, or a 3.5" magneto-optical disk cartridge, which is currently being standardized.

FIG. 6 is a structural diagram of a magneto-optical disk used in the present invention. Reference numeral 14 denotes a transparent substrate made of glass or plastic. Guide grooves, pre-pits or oblique bits are formed on the surface by the 2P method or injection molding. 15 is a protective film for preventing oxidation of the magneto-optical recording film 16, and is made of oxygen-free ceramic 1lI (for example, Al
2N, SiN, Ag5iN, ZnS, TiN, etc.) are often used. 17 is a resin protective film with a thickness of about 10 μm. The formation method is performed by UV irradiation after a spin code.The magneto-optical recording film 16 is an amorphous 74 film based on rare earth transition metals, for example, TbFe, DyF.
e, GdCo, TbCo, TbFeCo, DyFeCo
, GdTbFeC01GdDyFeCo, NdDyFe
Co, NdTbFeCo, etc. are used. Small amounts of Al2, Cr, Ti, and Pt may be added to improve durability. The protective film 15 and the magneto-optical recording film 16 each have a thickness of 1100
The thickness is about n. The electromagnet is located 200 μm away from the surface of the resin protective film 17.

By using the magneto-optical disk having the structure shown in Fig. 6 and the optical head, electromagnet, and height control mechanism shown in Fig. 1,
Overwriting from 00KHz to several MHz is possible.

[Effects of the Invention] As described above, according to the present invention, a magneto-optical disk can be housed in a normal cartridge, and the cartridge can be attached to and removed from an optical disk drive device. this is,
This is because the distance between the electromagnet and the magneto-optical disk can be set to about 200 μm using the height control mechanism. The present invention enables high-speed overwriting from several 100 KHz to several MHz. As a result, the host computer's waiting time is reduced and information processing efficiency is greatly improved.

It goes without saying that the present invention is not limited to the above-mentioned embodiments, and can be modified in many ways.For example, 1a in FIG.
If IA is applied to one Ej stone, it can be separated by up to 1 mm, and the height can be controlled to always maintain a distance of about 1 mm. The height detection mechanism may be not only optical, but also electrical or mechanical. Furthermore, the shape of the recording medium can be applied not only to a disk shape but also to a card shape.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a data rewriting method for an optical 6N recording/reproducing apparatus according to the present invention. FIG. 2 is a structural diagram of the height detection mechanism. FIGS. 3(a) to 3(c) are explanatory diagrams of the height detection method. FIG. 4 is a structural diagram of 11 magnets and a height control mechanism. FIG. 5 is a characteristic diagram of magnetic field strength versus distance between IT electromagnets. FIG. 6 is a structural diagram of a magneto-optical disk used in the present invention. FIG. 7 is a diagram explaining the principle of the conventional overwriting method (1). FIG. 8 is a diagram explaining the principle of the conventional overwriting method (2). FIG. 9 is a diagram explaining the principle of the conventional overwriting method (3). 1... Magneto-optical disk 2... Optical head 3... Frame 4... IT electromagnetic 5... Coil 6... Permanent magnet 7... Wire 8... ... Light emitting diode 9 ... Two-split photodiode 10 ... Mounting base 11 ... Differential amplifier 12 ... Ferrite core 13 ... Winding 14 ... Translucency Substrate 15... Protective film 16... Magneto-optical recording film 17... Resin protective film 100... Recording track lot... Control ready track 102... Erasing laser beam 103... ...Controlling laser beam 104...Recording/reproducing laser beam 105...Track address 106...Substrate 107...Recording layer 108...Protection layer 109...Slider 110...Magnetic head 111 ... Flying height 112 ... Focused laser beam 113 ... Memory layer 114 ... Auxiliary layer 115 ... Advance auxiliary magnet 116 ... Auxiliary magnet 117 ...: Disk rotation direction 118 ... New Data 119...Old data LOL light stone 8 (time Cj weak light gui f 斗゛? 20') 171 to 91 ding 1' 2nd er (ming) (b) (C) , A-town No. 5''

Claims (1)

[Claims] (1) A magneto-optical recording medium having a single-layer magneto-optical recording film is irradiated with a focused laser spot of a certain intensity, and the magneto-optical recording medium is placed at a position facing an optical head with the magneto-optical recording medium in between. By arranging an electromagnet with a height control mechanism that maintains a constant distance from the electromagnet and modulating the direction of the magnetic field generated by the electromagnet, overwriting
A data rewriting method for a magneto-optical recording/reproducing device, characterized in that: